GENEVA (AP) — Global warming accelerated since the 1970s and broke more countries' temperature records than ever before in the first decade of the new millennium, U.N. climate experts said Wednesday.

A new analysis from the World Meteorological Organization says average land and ocean surface temperatures from 2001 to 2010 rose above the previous decade, and were almost a half-degree Celsius above the 1961-1990 global average.

The decade ending in 2010 was an unprecedented era of climate extremes, the agency said, evidenced by heat waves in Europe and Russia, droughts in the Amazon Basin, Australia and East Africa, and huge storms like Tropical Cyclone Nargis and Hurricane Katrina.
Data from 139 nations show that droughts like those in Australia, East Africa and the Amazon Basin affected the most people worldwide. But it was the hugely destructive and deadly floods such as those in Pakistan, Australia, Africa, India and Eastern Europe that were the most frequent extreme weather events.

Experts say a decade is about the minimum length of time to study when it comes to spotting climate change.

From 1971 to 2010, global temperatures rose by an average rate of 0.17 degrees Celsius per decade. But going back to 1880, the average increase was .062 percent degrees Celsius per decade.

The pace also picked up in recent decades. Average temperatures were 0.21 degrees Celsius warmer this past decade than from 1991 to 2000, which were in turn 0.14 degrees Celsius warmer than from 1981 to 1990.

Natural cycles between atmosphere and oceans make some years cooler than others, but during the past decade there was no major event associated with El Nino, the phenomenon characterized by unusually warm temperatures in the equatorial Pacific Ocean. Much of the decade was affected by the cooling La Nina, which comes from unusually cool temperatures there, or neutral conditions.

Given those circumstances, WMO Secretary-General Michel Jarraud says the data doesn't support the notion among some in the scientific community of a slowdown, or lull, in the pace of planetary warming in recent years.

"The last decade was the warmest, by a significant margin," he said. "If anything we should not talk about the plateau, we should talk about the acceleration."

Jarraud says the data show warming accelerated between 1971 and 2010, with the past two decades increasing at rates never seen before amid rising concentrations of industrial gases that trap heat in the atmosphere like a greenhouse.

By the end of 2010, the report shows, atmospheric concentrations of some of the chief warming gases from fossil fuel burning and other human actions were far higher than at the start of the industrial era in 1750. Carbon dioxide concentrations measured in the air around the world rose 39 percent since then; methane rose 158 percent; and nitrous oxide was up 20 percent.

World suffered unprecedented climate extremes in past decade: WMO Photo: NASA
Earth's airglow is seen with an oblique view of the Mediterranean Sea area, including the Nile River with its delta and the Sinai Peninsula, in this October 15, 2011 NASA handout photograph taken by a crew member of Expedition 29 aboard the International
Photo: NASA

The world suffered unprecedented climate extremes in the decade to 2010, from heatwaves in Europe and droughts in Australia to floods in Pakistan, against a backdrop of global warming, a United Nations report said on Wednesday.

Every year of the decade except 2008 was among the 10 warmest since records began in the 1850s, with 2010 the hottest, according to the study by the World Meteorological Organization (WMO). The number of daily heat records far outstripped lows.

It said many extremes could be explained by natural variations - freak storms and droughts have happened throughout history - but that rising emissions of man-made greenhouse gases also played a role.

"Rising concentrations of heat-trapping greenhouse gases are changing our climate, with far-reaching implications for our environment and our oceans, which are absorbing both carbon dioxide and heat," WMO Secretary-General Michel Jarraud said in a statement.

The study said damaging extremes included Hurricane Katrina in the United States in 2005, Cyclone Nargis in Myanmar in 2008, floods in Pakistan in 2010, droughts in the Amazon basin, Australia and East Africa and a retreat of Arctic sea ice.

Deaths from extreme events totaled 370,000 people, up 20 percent from the 1990s, the Geneva-based WMO said, though the world population also rose sharply over the period, from 5.3 billion in 1990 to 6.9 billion in 2010.

The jump in the death toll was caused mainly by a heatwave in Europe in 2003 which killed 66,000 and a heatwave in Russia in 2010 in which 55,000 people died.

However, casualties from storms and droughts fell, partly because of better preparedness for disasters.

The study said that 44 percent of nations recorded the highest daily maximum temperature of the past half-century in the decade 2001-10 but only 11 percent reported a new low.

It also said that the decade "continued an extended period of accelerating global warming" with average decadal temperatures 0.21 degree Celsius (0.4 F) warmer than 1991-2000, which was in turn 0.14 C warmer than 1981-1990.

SLOWING RATE OF INCREASE?

Other reports have found that the rate of temperature rises has slowed this century.

"Global mean surface temperatures have not increased strongly since 1998" despite rising greenhouse gas emissions, according to a draft report by the U.N.'s panel of climate scientists due for release in September.

Some experts say the apparent rise from the 1990s is magnified because a volcanic eruption in the Philippines in 1991 dimmed sunlight and cut temperatures.

The WMO also said it was hard to link any individual extreme events to climate change rather than to natural variability.

However, warmer air can hold more moisture, raising risks of downpours - the study said that 2010 was the wettest year since records began. And sea levels have risen about 20 centimeters in the past century, increasing risks of storm surges.

One 2004 study, for instance, said that climate change had at least doubled the risks of the European heatwave in 2003.

Peter Stott of the UK Met Office who led that study said scientists were now trying to see if there was a human fingerprint behind other extremes in 2012, such as Superstorm Sandy or drought in Australia.

"You can't just take a record-breaking event and say 'that's climate change'," he said.

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